Modern approaches to the study of probiotics in aquaculture: histological and molecular genetic analysis of the effects of Bacell-M on common carp (Cyprinus carpio)

A 35-day experiment was conducted on two groups of fish (control and experimental, n=600 in each). The experimental group received a diet supplemented with "Bacell-M" at a dosage of 2 kg per ton of feed. The analysis utilized light microscopy of histological sections of muscle tissue stained with hematoxylin and eosin, and the real-time PCR method to assess the expression of the LPL (lipoprotein lipase), FASN (fatty acid synthase), and FABP3 (fatty acidbinding protein) genes. Additionally, zootechnical indicators such as weight gain, feed conversion ratio, and survival rate were recorded. It was found that the use of the probiotic "Bacell-M" significantly improved the histoarchitecture of the muscle tissue, manifested in the uniformity of muscle fiber diameter, clear organization of myofibrils, and the absence of dystrophic signs. Molecular genetic analysis revealed a significant increase in the expression of LPL (by 3.7 and 4.2 times on days 14 and 35, respectively) and FABP3 (by 2.1 times) genes, as well as a decrease in the expression of the FASN gene (by 3.0 and 2.7 times), indicating an intensification of lipid utilization and a reduction in their de novo synthesis. This correlated with improved production indicators: the relative weight gain in the experimental group was 26.2% compared to 15.5% in the control, the feed conversion ratio improved (1.28 vs. 1.51), and the survival rate increased to 98.7% compared to 91.8%. The probiotic "Bacell-M" has a pronounced positive effect on the morphofunctional state of the skeletal musculature in carp, optimizing lipid metabolism at the molecular level. This leads to an acceleration of growth rates, improved feed efficiency, and increased survival. The preparation is a promising, biologically safe alternative for use in modern aquaculture.

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